Snap-In Tube Caps, These are replacement caps for the alluminum material loading bars that came with your Gerber GS-750 Plotter. After years of use, the caps can wear down and eventually fall out of the material loading bars. Without the caps installed, the bars are not long enough to fill the space correctly, which can result in the bars falling out of the bar holds on your plotter. Simply replace the caps and get the bars to working perfectly again. Each Order will include 2 caps.